Surprisingly, the so-called airless systems typically employ fans or propellers to move large masses of ambient air. One problem found with both systems but particularly with the airless systems using the propellers or fans for the large volume movement of air is that a portion of the output of these systems consists of partially frozen snow or water and water spray.
This partially frozen snow or water or water spray, hereinafter collectively referred to as ice particles, even under optimum conditions may eventually fall or are drawn into the housing of a snow-making machine causing icing. The problem of icing is particularly acute when the wind direction changes and the ice particles are blown back toward the snow-making machine. In this circumstance large amounts of ice particles fall in the housing causing icing and more importantly are drawn into the housing by the fan causing icing on the fan to the degree that the machine must eventually be shut down and ice removed before further operation.
This blow back under certain conditions of wind will therefore recirculate through the inlet or upstream portion of the snow-making machine and freeze up on the inlet screen and the fan. This eventually causes blockage of the inlet and shut down of the snow-maker and/or causes destructive unbalance of the fan which is rotating at a high speed.
It is not always possible to operate snow-makers in a manner to prevent this blow back. When a steady wind exists it is often possible to point the machine downwind and eliminate the blow back but as a practical matter it has been found that the winds change, often the wind is gusty and not uniform in direction.
This problem was substantially overcome in U.S. Pat. No. 3,948,442. However, even with the invention of that patent there is still a small percentage of fines which remain suspended in the air and may eventually drift back and fall on or be drawn into the housing. Also, depending on atmospheric conditions, that is, natural precipitation may also result in the presence of ice particles.
Conventional separators to remove ice particles from the air prior to its entry into the housing of a snow-making machine are not suitable. Conventional separators which rely upon large diameters to reduce the pressure of a fluid to precipitate out entrained materials are unwieldy and costly. Also, the precipitated ice would tend to accumulate in the separator requiring costly removal such as with heating elements. This same problem of ice accumulation would also occur with centrifugal separators, mist eliminators, etc.
I have now discovered that the problems of icing particularly on snow-making machines may be eliminated in either one of two ways or by utilizing both ways. Both techniques employed relate to reducing the bond between the ice particles and the protective screen upstream of the fan and/or between the ice particles and the surface of the rotating fan thereby preventing accumulation of the same on either the screen and/or fan.